Experimental Investigation on the Ground Temperature Profile for Shallow Geothermal Energy Applications in a Hot and Dry Climate

Abstract

To reduce the dependence on electrical energy for heating and cooling systems in hot and arid climate areas, shallow geothermal energy as a local energy source represents a promising alternative. In this regard, it is essential to know and understand the ground temperature profile to design shallow geothermal applications and estimate the energy contribution. Many parameters influence the ground temperature profile, such as soil properties, surface cover, soil moisture, degree of compaction...etc. The variation of these parameters affects the damping depth of the annual fluctuation of ground temperature and the thermal diffusivity. Accordingly, the present study investigates experimentally the ground temperature profile subjected to the variation of two selected parameters on the ground response time and the damping depth. These parameters are solar radiation and ground humidity. The ground temperatures were measured and then used to present the temperature distribution profiles. The measurement site is in Madinah (lat. of 24.5° N and long. of 39.5° E), KSA, characterized by a hot and arid climate, where the temperature in summer exceeds 48.0 °C. A well of 14 m depth and 7.5 cm diameter is drilled in the site, and 15 thermocouples (T-type) are used to measure the ground temperature at different depths. Results show that the ground temperature as a geothermal energy source is sensitive to solar radiation and soil humidity, especially near the ground surface. These parameters can influence the design and operation of EAHE.